MatPlotLib X axis with dates

Question

I have a graph within a GUI which opens with a button click. It opens from a csv file that constantly updates, hence the counting at the beginning, I wanted to limit the number of entries for the x-axis.

The plot works for the four lines however, I have been unable to refine the x axis, what I would like to do is;

1. Rotate the font
2. Remove the trailing zeros for the dates
3. Possibly Change the Date Format to DMY H:M

The Below script is what I have so far:

def open_graph():
    import numpy as np
    import matplotlib.pyplot as plt
    import datetime as dt 
    from dateutil import parser
    from csv import reader
    with open('Voltage_Readings.csv','r') as f:
        data = list(reader(f))

    file=open('Voltage_Readings.csv')
    numlines=(len(file.readlines())-1)
    start=numlines-100
    end=numlines

    fig=plt.figure()
    ax=plt.subplot(111)

    DTG = [parser.parse(i[1]) for i in data[start:end]]
    Battery_Level = [i[2] for i in data[start:end]]
    Gene_Supply = [i[3] for i in data[start:end]]
    Solar_Supply = [i[4] for i in data[start:end]]
    Wind_Supply = [i[5] for i in data[start:end]]

    plt.plot(DTG, Battery_Level,'-r', label='Battery')
    plt.plot(DTG, Gene_Supply,'-y', label='Gene')
    plt.plot(DTG, Solar_Supply,'-b', label='Solar')
    plt.plot(DTG, Wind_Supply,'-g', label='Wind')

    box = ax.get_position()
    ax.set_position([box.x0, box.y0, box.width *0.85, box.height])
    ax.legend(bbox_to_anchor=(1, 1),loc=2)

    plt.title('VOLTAGE MEASUREMENTS FROM POWER SOURCES')
    plt.xlabel('Time')
    plt.ylabel('Voltage')

    plt.show()

I would appreciate any assistance is being able to achieve this as I am still learning.

Answer 1

Here is a better answer:

Just add this before your plt.show() command:

fig.autofmt_xdate()
import matplotlib.dates as mdates
ax.fmt_xdata = mdates.DateFormatter('%d-%m-%Y %H:%M')
datetimefmt = mdates.DateFormatter("%d-%m-%Y %H:%M")
ax.xaxis.set_major_formatter(datetimefmt)

Running autofmt_xdate makes the dates slanted. Setting ax.fmt_xdata sets the date format when you hover your mouse over a point. Running ax.xaxis.set_major_formatter sets the date format on the x axis.

Interestingly enough in my own matplotlib code I've done my own formatting of the dates on the x axis because I wasn't aware of these auto formatting features. I'm going to have to revise my code to use what's already in matplotlib.

Bobby